1. Field of the Invention
This invention relates generally to coke oven doors, and particularly to coke oven doors which assure a good seal between the door and jamb, and which are constructed so as to prevent warping of the door and/or jamb during operation of the associated oven.
2. Description of the Prior Art
Coke ovens are conventionally provided with two doors at any given site, one side of the oven being called the coke side and the other side being called the pusher side. The pusher side door has a small door or hatch covering an opening provided in the top end of the door, this small door hatch generally being designated as a "leveler door". The coke side door is a flush door without any other openings.
A difficulty encountered with these doors is that carbon and other foreign matter get between the door and assoicated jamb surface of the oven and cause sticking of the abutting door and jamb surfaces. Also, in addition to sticking, the accumulation of carbon and other foreign matter creates a fire hazard.
Another problem encountered with coke oven doors is that the door tends to warp in the shape of chair rocker, with the middle of the door seal touching the sealing surface of the associated jamb and pulling away from the jamb sealing surface at the top and bottom thereof. As a result of such warping, as well as the difficulty of achieving tight seals between the door and jamb, one of the greatest problems encountered today at coke oven sites is leakage of smoke and gas at the doors. In addition, there is a problem with leakage of flame up the sides of doors causing warpage of jambs and buck stays. This damage is very costly and is a great cause of air pollution.
Various proposals have been made for improving the seal between a coke oven door and its associated door jamb. For Example, U.S. Pat. No. 890,175, issued June 9, 1908, to H. Ries, discloses a furnace door provided with a plurality of pressure springs adjustable by associated bolts to vary the pressure over the surface of a door plate of the oven door. The knife edge which provides the seal of the Ries device, however, is of the same general kind as used on sealing edges of oven doors today, with this knife edge running all around an associated packing ledge and being compressed by the aforementioned pressure springs. The latter are equally spaced between upper and lower knife edges, but the spaces between the spring spaces tend to become disfigured, and there is a possibility of leaks along the knife edge when same has been subjected to heat for a substantially length of time. That is, the knife edge arrangement as disclosed in the Ries patent operates well until heat and age cooperate to disfigure the entire knife edge, and then no further adjustment can be made to the sealing edge to achieve a good seal.
U.S. Pat. No. 2,442,348, issued June 1, 1948, to R. E. Exum, discloses a self-sealing coke oven door which is also similar to the construction commonly used today. When the sealing edge of this arrangement makes sealing contact with jamb sealing surfaces, it makes contact in a similar manner to placing a straight edge on the edge thereof on any flat surface. On the machine sealing surface of the jamb, hard carbon will build up in places and this kind of seal will not penetrate the carbon, leaving leakage between the areas of carbon build-up. The sealing edge is compressed by a bolt which is supported by a main frame, making this arrangement a fixed seal. When this fixed seal is under pressure from associated springs, that is to say when there is warpage of the associated jamb or of the door frame, an undesirable adjustment of the associated adjustment bolts must be made in the field. These adjustment bolts are either over adjusted or under adjusted, causing a leak to occur at some other location around the sealing edge. Further, both the frames of U.S. Pat. Nos. 890,175 and 2,442,348 are rigid frames, which means that when the frame becomes warped and can be adjusted no further by the adjusting bolts, the frame must be either straightened or replaced. In particular, the frame disclosed in U.S. Pat. No. 890,175 has a tendency to bow outward from the heat of the oven while the associated jamb has a tendency to bow inwardly. This occurs in all coke oven batteries. After some time of use, this type of door frame and sealing edge run out of adjustment and have to be repaired or replaced. Further, there are some undesirable friction points in this general mode of construction.
U.S. Pat. No. 3,881,995, issued May 6, 1975, to H. A. White, Jr., discloses a method and apparatus for sealing a coking chamber in which the sealing edge is similar to the other sealing edges used today. The White proposal adds a member which makes the sealing edge a wider sealing surface, but this kind of seal is sometimes too wide to penetrate carbon left on the sealing surfaces of the associated jamb. Further, the frame of U.S. Pat. No. 3,881,995 is rigid, as are those discussed above, while a leveler door disclosed in U.S. Pat. No. 3,881,995 is generally the same as those commonly used today, except for the addition of a cover. The use of this cover works well until the associated door becomes warped, and then leakage will occur by the cover.
U.S. Pat. No. 3,984,310, issued Oct. 5, 1976, to A. Calderon, discloses an apparatus for minimizing accumulation of deposits between the door and associated jamb of a coke oven in which a burner is provided at the edge of the door in order to burn off any deposits lying between the door and the door jamb. The sealing edge of this apparatus is generally the same as sealing edges commonly used today. The burners have been applied to burn off carbon and other matter by means of a combustible mixture installed in the door frame or in the door jamb, as desired. Further, U.S. Pat. No. 3,875,018, issued Apr. 1, 1975, also to A. Calderon, discloses a coke oven door provided with a heat settable sealant for forming a positive seal between the door and the jamb of an oven in order to plug the crevices through which gas might otherwise escape. The latter mentioned prior patent actually brings out quite clearly the difficulties encountered with trying to obtain a tight seal between a door and associated jamb using the door constructions commonly used today.
U.S. Pat. No. 3,149,615, issued Sept. 22, 1964, to P. E. Forsans, discloses a vaporizing jamb frame for oven doors wherein steam fills a sealing chamber provided between the door and jamb and insures the tightness of the oven door, while U.S. Pat. Nos. 144,857, issued Nov. 25, 1873, to P. Munzinger, and 491,769, issued Feb. 14, 1893, to J. P. Clark, disclose examples of tight-fitting covers for retorts.